DanielsDM introduced a new word "fuel container" which I think has no place in this discussion as it muddies the water.

As said, NASA rules state a barrier is needed.
15.4 Fuel Cell / Tank
All fuel cells must be FIA FT3 (or higher) certified.
A fuel cell is not required, except as specified by class rules.. All vehicles having a fuel cell must comply with
the rules in this section, even if a fuel cell is not required by the class rules.
1. There should be a solid bulkhead completely separating the fuel tank, fuel pump, fuel cell, filler neck
hoses, and/or vent lines, from the driver compartment.

I'm not a tech guy either but I see the difference in the use of the word "tank" and "fuel cell". A "tank" denotes a stock tank in its stock location, which means it has a barrier intrinsic to the car, or as manufactured. I don't think DOT allows cars to be sold without a barrier being between the tank and passengers.
A "fuel cell", when not behind the stock barrier, or with exposed fittings and hoses, does not have a barrier if anything is exposed. Fuel could spray out into the cockpit from a line or fitting without a barrier. So, once you install a fuel cell in a non-stock location the barrier must be constructed.
My 2 cents.
I also agree that oil is often what catches fire and just hot oil can burn you severely. I am now going to enclose my Accusump and fittings (which is in the passenger floorboard area of my STi) because of this or move it back to the engine compartment.
I think it's a serious lapse of safety (for the participant) that I can run a almost race legal, prepared car at a "track day" or HPDE event without meeting some of the fire safety standards of NASA/SCCA racing.